1. Field of the Invention
The present invention relates generally to the manufacture of industrial drums and pertains, more specifically, to the rotational molding of industrial drums of synthetic polymeric materials in the closed-head configuration and in the open-head configuration of such drums.
2. Description of the Related Art
Industrial drums constructed of synthetic polymeric materials and emulating structural features of commercially available conventional steel industrial drums have been manufactured successfully by rotational molding and have met with widespread commercial acceptance. As set forth in U.S. Pat. No. 4,094,432, desirable structural features of conventional industrial drums can be carried over into industrial drums constructed of synthetic polymeric materials, while added advantages provided by the use of a synthetic polymeric material, such as corrosion resistance and ease of maintenance, are realized.
Industrial drums of the type described above generally are supplied in two basic configurations; namely, the closed-head configuration in which the head of the drum is unitary with the body of the drum, and the open-head configuration, in which the head is selectively attached to and detached from the body of the drum. The relatively large facilities and extensive molding apparatus required for the rotational molding of industrial drums, coupled with the usually mixed demand for one or the other of the above-described drum configurations, militate against dedicating an entire production facility to the manufacture of just one of the drum configurations. Since the demand for one or the other of the two drum configurations may vary from time to time, it would be advantageous to be able to select the number of each of the two configurations to be molded in any particular production run, without the necessity for extensive changes in tooling and the consequent delay engendered by the necessity for making tooling changes in the production apparatus.